It is increasingly common for an automotive vehicle to utilize a centralized electronics control module. Such modules incorporate electronic circuits that regulate and route electronic signals to selected components throughout the automobile. The functions of these modules may include, for example, circuit breakers, windshield wiper circuits, interior chime circuitry, power window circuitry, door lock circuitry, and an array of fuses and relays. These types of control modules are typically located in the instrument panel area, thereby allowing easy accessibility from both the engine compartment and the vehicle interior.
However, not all control modules are located in the area of the instrument panel. For example, powertrain control module, or the PCM, is not so positioned. The PCM is a control module that is the “brain” of the vehicle and, as such, conventionally incorporates multiple control units, such as the engine control unit (the ECU) and the transmission control unit (the TCU). Accordingly, with respect to engine operation, the PCM typically controls ignition, fuel injection and emission.
Because of its operational relationship with the engine and transmission, the PCM is mounted in a variety of locations proximate to these components, including the dashboard support panel and under the engine hood in the engine compartment where it is often but not exclusively attached to a sheet metal body structure. The location of the PCM is dictated by certain conditions including space and service accessibility. Accordingly, the final position of the PCM varies from vehicle to vehicle. If positioned under the engine hood, the PCM may be fixed to locations such as the firewall, the wheel well or the battery bracket and, in certain cases, to the engine itself. Typically, the PCM includes a mounting bracket that allows for firm mounting to the selected mounting surface. The bracket is conventionally attached by, for example, mounting bolts.
Known PCM mounting brackets are typically formed from sheet metal although certain applications where water-proofing, anti-theft protection and weight reduction are desired require that the bracket be formed from a rigid plastic such as ABS (acrylonitrile butadiene styrene) plastic. When formed from a plastic, known brackets offer suffer from defects such as undesirable weld lines, white marks, sink marks and warpage due to the molding process. Given its strategic location on engine compartment walls or on other structural elements, the PCM is required to endure dynamic road loads that risk damage to the PCM bracket. Such damage typically arises in the form of failure cracks that appear over its superior surface. It has been identified that the maximum Von Mises stress of some bracket designs was higher than the yield stress of the plastic material (for example, 42 MPa of polypropylene PPTV20). In this case, the component was subjected to levels of stress that were too high resulting in some areas that experience plastic (permanent) deformation during CAE simulations. As a result of the situation in which the support bracket for the PCM may fail in some extreme cases, engine and drivetrain failure are both possible.
In view of the limitations of known metal and plastic brackets having a recessed area for a module due to the above-noted undesirable characteristics, a new approach mounting a PCM to a vehicle to prevent structural failure is needed.